RUNOFF AND EROSION FROM A MOSAIC TOBOSAGRASS AND BURROGRASS COMMUNITYIN THE NORTHERN CHIHUAHUAN DESERT GRASSLAND

A mosaic plant community pattern was studied in the northern Chihuahua n Desert grassland region of sourthern New Mexico. The principal plant species of the mosaic were tobosagrass (Hilaria mutica (Buckl.) Benth .) and burrograss (Scleropogon brevifolius Phil.). Water runoff, sedim ent concentration, incremental sediment, and plant and soil properties of both species aggregations were measured. The study site was a larg e aggregation of burrograss plants in a tobosagrass matrix. Water runo ff was three times greater from the burrograss aggregation than from t he tobosagrass aggregation both before and after the growing season. S ediment concentration and cumulative sediment loss were also greater f rom the burrograss than the tobosagrass, except under wet conditions i n the early autumn when sediment concentrations were similar. Differen ces are attributed to greater cover, phytomass, and surface roughness in the tobosagrass aggregation. (C) 1998 Academic Press Limited.